Electrical character select mechanism for typewriter

ABSTRACT

An electrical character select mechanism for a typewriter of the single printing head type, for example the IBM Selectric, where the selector latches which control tilt and rotation of the printing head are actuated by a number of relays specially located and shaped.

O United States Patent [is] 3,647,042

Smith 1 1 Mar. 7, 1972 [54] ELECTRICAL CHARACTER SELECT 3,391,774 7/1968 Greer .....l97/19 MECHANISM FOR TYPEWRITER- 3,414,103 12/1968 Knudsen et al. ....197/20 3,516,528 6/1970 Davidge et a1. 197/16 [72] Inventor: Roland T. Smith, San Francisco, Calif.

Primary Examiner-Robert E. Pulfrey [73] Asslgnee' Corporation Assistant Examiner-Clifford D. Crowder [22] Filed: July 20, 1970 Attorney.lay OMalley, Jr. and John F. Lawler 21 App1.No.: 56,541 [57] ABSTRACT f An electrical character select mechanism for a typewriter of [52] US. Cl ..l97/l9, 197/16 the Single priming head type, for exampb the IBM selectric, f 1 5/30 where the selector latches which control tilt and rotation of [58] F leld of Search ..l97/ l9, 16 th riming head are actuated by a number of relays specially located and shaped. [56] References Cited 3 Claims, 5 Drawing Figures UNITED STATES PATENTS 3,233,715 2 /1966 Flieg 197/ 1g ELECTRICAL CHARACTER SELECT MECHANISM FOR TYPEWRITER BACKGROUND OF THE INVENTION In general, the pressing of a key button positions a character in the printing position by rotating and tilting the printing head predetermined angles. The amount of tilt or rotation is in general detennined by the typewriter mechanism mechanically decoding what is in efiect a binary six-bit code. In other words, when a type button is pressed, a unique combination of six levers is in effect actuated. These levers are mechanically coupled to the printing head in such a manner that the six-bit binary lever code is decoded by the linkage of the printing head to tilt and rotate it to a character position.

Where an automatic character select mechanism is desired, relays may be coupled to the appropriate levers to actuate them. One of the major elements of a typical IBM typewriter which is actuated by a prior system is termed the latch interposer. This creates a need for a relatively large relay force and is complex mechanically and, therefore, unreliable. Another method of electrically selecting characters is to actuate what is known as a selector latch lever. This was done in the past by use of a rather complex and expensive relay arrangement. Another factor in providing suitable actuating relays for character selection is that the automated typewriter should still have a relatively low profile to present the proper height to a typist using a desk or typing stand of standard height.

SUMMARY OF THE INVENTION AND OBJECTS It is, therefore, an object of the present invention to provide an improved electrical character select mechanism for a typewriter.

It is another object of the invention to provide a mechanism as above which is simple, inexpensive and mechanically compact.

In accordance with the above objects the present invention relates to a typewriter having a printing head with a plurality of characters arranged thereon and operable by a corresponding plurality of type keys to present one character at a time to a printing position. Selector interposer means are provided for each of the type keys. Each of the interposer means has a plurality of selector lugs uniquely positioned forming notches. A plurality of latch interposer means having single lugs are also provided. A plurality of selector bails are included which extend through the notches. Each of the bails also extend in front of a lug of an associated latch interposer means. Actuation of a key initiates movement of an associated selector interposer means which in turn moves a combination of the bails determined by the unique lugs. The bails move into contact with the lugs of the latch interposer means to move such means. Selector latch means are coupled to the latch interposer means and to the printing head and are responsive to movement of a predetermined combination of the latch interposer means to effect selective rotation and tilting of the printing head. At least two of the selector latch means are coupled to the printing head by a ball and socket joint. The joint has a ball portion rigidly mounted to the selector latch means with the ball portion having a stud extension.

The improvement of the present invention comprises a plurality of relay means for selectively actuating the selector latches. Included are a plurality of solenoid means mounted to the frame of the typewriter each having a pivot axis on which associated actuator levers are pivoted. The pivot axes are displaced from the stud extensions both horizontally and vertically with reference to the axis of the stud extension. Each of the actuator levers has an L-shaped end for engaging the stud extension of an associated selector latch means when the associated solenoid is energized for rotating the latch means.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a perspective view of a portion of a typewriter showing how the invention is related to the normal working parts of the typewriter;

FIG. 2 is an enlarged elevational view of a portion of FIG. 1 and shows additional structure embodying the present invention;

FIG. 3 is a cross-sectional view substantially taken along the lines 3-3 of FIG. 2; and

FIGS. 4A and 4B are two cross-sectional views of a portion of FIG. 2 showing that portion in two different operating conditions.

DETAILED DESCRIPTION or THE PREFERRED EMBODIMENT Referring to FIG. 1, several of the components shown are generally like those disclosed in the Palmer patent mentioned above. This typewriter includes a representative key button 10 mounted on a key lever 11 which is pivoted on a rod 12. The key button and lever are, of course, associated with a specific character. Attached to each key lever 11 is a key lever pawl 13' which is held in its rest position by a spring 14. Pawl 13 exstrike the top of a selector interposer 16.

The purpose of interposer 16 is to select the amount of tilt and rotation needed to bring the desired character toits printing position. A large fulcrumed rod 17 passes through an elongated hole in the front of each interposer lever (only one of which is, of course, shown in FIG. 1) and provides the support on which the interposers pivot and slide.

The interposers 16 have several lugs 18 extending from them each with its own operation to perform. The absence or presence of these lugs in different position combinations makes each interposer unique. One lug 18a is common to all interposers its purpose being to initiate the operation cycle whenever a key lever is depressed. This is accomplished by a cycle bail I9 which is directly beneath lug 18a which when key button 10 is pressed causes the pawl 13 to move interposer l6 and thereupon lug 18a actuates the cycle bail 19 to initiate the cycle of operation of the typewriter for that particular character selected.

Part of the cycle of operation is the rotation of a filter shaft 21. When interposer 16 is depressed the rear of the interposer is moved down in front of one blade of the filter shaft and as the filter shaft turns the blade drives the interposer forward to ultimately operate the character selection mechanism.

Six selector bails, two of which 22 and 23 are shown, extend through the notches formed by lugs 18 and also in front of lugs 24a and 26a of character selector latch interposers 24 and 26. Movement of interposer l6 forward as shown by arrow 27 by filter shaft 21 moves selector bails 22 and 23 forward to move forward the associated latch interposers 24 and 26. It is, of course, assumed that in this example interposer 16 would not have lugs for any of the other bails. The bails 22 and 23 and of course the other four bails (not shown) and the latch interposers (only two of which are shown) are paired so that each bail operates only one latch interposer. Extension springs 24b and 26b at the bottom of each latch interposer loads the interposer and its selector bail to the rear.

Additional link means 24c and 260 couple each latch interposer to selector latches 28 and 29 These selector latches are ultimately coupled to the printing head of the typewriter in a manner well illustrated in the Palmer patent to effect the proper angle of rotation and tilting.

Such coupling is in part shown in FIG. 3 where the latches 28 and 29 serve as tilt latches and are attached at each end of a short lever 31 by ball shouldered rivets 32 and 33, respectively. FIG. 4A shows an enlarged view of this ball shouldered rivet which in effect forms a part of a ball and socket joint with a ball portion 34 rigidly mounted in the selector latch 29 the ball portion having a rivet or stud extension 36. An aperture in lever 31, of course, provides the socket. Lever 31 is attached to a tilt bellcrank 37 by a vertical link 38. Tilt bellcrank 37 is coupled by a horizontal link 39 through a tilt arm which ultimately is coupled by a flexible tape to the printing head to tilt it in accordance with the character selected.

In operation when the typewriter is being keyed manually a latch interposer is moved forward and the selector latch coupled to that interposer is normally pulled forward by link 26c as illustrated in FIG. 4B. This pulls the latch free of selector latch bail plate 41 which is a part of a latch bail 40 which is capable of movement as shown by the arrow 42 in FIG. 4B.

As is more clearly shown in FIG. 3, when the left latch 28, for example, is held against bail plate 41 while the right latch is pulled away only the right latch 29 is forced down by bail plate 41. As the latch pulls down on its attached lever the left end of the lever pivots against a stop lug 45 fastened to the frame of the typewriter and the vertical link 38 is then pulled to operate tilt bellcrank 37. The same action occurs if the left latch 28 is pulled down by the bail 41 and the right latch has been pulled free, as illustrated in FIG. 4B. Since the distance the vertical link 38 is pulled is not the same for both latches because of the asymmetrical connection of the link to the horizontal lever 31, two different amounts of tilt are provided. Thus, it is also apparent how proper increments of rotation of the printing head are also achieved.

Thus in summary, whether or not a latch 28 or 29 along with the other four latches (not shown) is pulled forward forms in effect a six-bit binary code. As shown in the Palmer patent and as explained above a predetermined combination of movements of the latches effect selective rotation and tilting of the printing head.

In accordance with the present invention a plurality of relay means are provided for selectively actuating the selector latches only one of which, latch 29, is illustrated in FIG. 2. The relay means include a plurality of electromagnets, a representative one 43 being shown mounted to frame 44 of the typewriterv Electromagnet 43 has a pivot axis 46 on which an associated actuator lever 47 is pivoted.

Pivot axis 46 is displaced from the stud extension 36 both horizontally and vertically with reference to the axis 48 of stud extension 36. Actuating lever 47, which is representative of four actuating levers all in a line, includes an L-shaped end 47a for engaging stud extension 36 of the associated selector latch. This occurs when solenoid 43 is energized. Upon engagement as illustrated in FIG. 4B, latch 29 is rotated free of bail plate 41.

The displacement of pivot axis 46 from stud extension 36 is such that the majority of force is applied in a vertical direction perpendicular to the stud extension axis 48. This is illustrated in FIG. 48 by the force vector 49 which is closer to a vertical position than a horizontal one. From a geometrical standpoint, if a line 51 is drawn from the pivot axis 46 substantially to the end of lever 47 or stud 36 the angle the line makes with the horizontal, designated must be less than 45 to provide a majority of force in the vertical direction. This, of course,

means that the tangent of the angle is less than one. From an actual measurement standpoint, the ratio of the vertical and horizontal legs of the triangle to provide such angle is 4.7 centimeters/6.6 centimeters.

In actual use, the relays represented by electromagnet 43 and lever 47 consist of four relays to operate what is normally termed the tilt l and tilt 2 latches and the rotate l and rotate 2 latches. The two remaining latches which are operated in another manner are termed the rotate 2A latch and the negative 5 latch. These are not illustrated in FIG. 2.

Thus, the present invention provides an improved character select mechanism by the unique placement and shape of the relays necessary for actuating the various latches. The shape of actuator lever 47 compensates for tolerance deviations and helps to maintain a low profile for the overall typewriter. The

reliabilitypf the relay actuators is in art due to the fact that the ma ority of the force IS in a vertlca direction and IS applied to the stud extension of the universal joint.

I claim:

1. In a typewriter having a printing head with a plurality. of characters arranged thereon and operable by a corresponding plurality of type keys to present one character at a time to a printing position, selector interposer means for each of said type keys, said interposer means having a plurality of selector lugs uniquely positioned and forming notches, a plurality of latch interposer means having single lugs, a plurality of selector bails extending through said notches, each of said bails extending in front of a lug of an associated latch interposer means, actuation of a key initiating movement of an associated selector interposer means which in turn moves a combination of said bails determined by said unique lugs, said bails moving into contact with said lugs of said latch interposer means to move such means, selector latch means coupled to said latch interposer means and to said printing head and responsive to movement of a predetermined combination of said latch interposer means to efiect selective rotation of said printing head, at least two of said selector latch means being coupled to said printing head by a ball-and-socket joint, said joint having a ball portion rigidly mounted to said selector latch means and the ball portion having a stud extension, wherein the improvement comprises: a plurality of relay means for selectively situating said selector latches including a plurality of solenoid means mounted to the frame of said typewriter, each of said solenoid means having a pivot axis on which associated actuator levers are pivoted, said pivot axis being displaced from said stud extension both horizontally and vertically with reference to the axis of said stud extension, each of said actuating levers having an L-shaped end for engaging said stud extension of an associated selector latch means when said associated solenoid is energized for rotating said latch means.

2. A typewriter as in claim 1 where at least one of said pivot axes is displaced so that the majority of force applied to said stud extension is applied in a vertical direction perpendicular to said stud extension axis.

3. A typewriter as in claim 2 where four are displaced.

of said pivot axes 

1. In a typewriter having a printing head with a plurality of characters arranged thereon and operable by a corresponding plurality of type keys to present one character at a time to a printing position, selector interposer means for each of said type keys, said interposer means having a plurality of selector lugs uniquely positioned and forming notches, a plurality of latch interposer means having single lugs, a plurality of selector bails extending through said notches, each of said bails extending in front of a lug of an associated latch interposer means, actuation of a key initiating movement of an associated selector interposer means which in turn moves a combination of said bails determined by said unique lugs, said bails moving into contact with said lugs of said latch interposer means to move such means, selector latch means coupled to said latch interposer means and to said printing head and responsive to movement of a predetermined combination of said latch interposer means to effect selective rotation of said printing head, at least two of said selector latch means being coupled to said printing head by a ball-and-socket joint, said joint having a ball portion rigidly mounted to said selector latch means and the ball portion having a stud extension, wherein the improvement comprises: a plurality of relay means for selectively situating said selector latches including a plurality of solenoid means mounted to the frame of said typewriter, each of said solenoid means having a pivot axis on which associated actuator levers are pivoted, said pivot axis being displaced from said stud extension both horizontally and vertically with reference to the axis of said stud extension, each of said actuating levers having an L-shaped end for engaging said stud extension of an associated selector latch means when said associated solenoid is energized for rotating said latch means.
 2. A typewriter as in claim 1 where at least one of said pivot axes is displaced so that the majority of force applied to said stud extension is applied in a vertical direction perpendicular to said stud extension axis.
 3. A typewriter as in claim 2 where four of said pivot axes are displaced. 